Torus

R=3;r=1;
ParametricPlot3D[{Cos[u]*(R+r*Cos[v]),Sin[u]*(R+r*Cos[v]),r*Sin[v]},{u,0,6},{v,0,6}]
(*
R is the distance from center of torus to tube center.
r is the radius of the tube.
u controls the torus sweep.
v controls the tube's profile sweep.
*)